RESUMO
BACKGROUND: The improvement of surface coverage and plant protection products deposition can be obtained by electrifying droplets, which are strongly attracted by plants, including the abaxial part of the leaves. Moreover, air assistance improves droplet penetration into the crop canopy, especially in the lower third of the plants. These technologies can help control soybean (Glycine max) whitefly, which preferentially lodges on the abaxial surface of the leaves. Thus, this study aimed to assess the effect of air-assisted spraying and electrically charged droplets to control whitefly in soybean, besides assessing surface coverage, plant protection product deposition, droplet size, and crop yield. RESULTS: Droplet electrification and air assistance did not change droplet size and uniformity classified as Fine. Surface coverage was not enhanced using air assistance and electrically charged droplets, where maximum coverage in the middle third of the plants was 4.55%. The results were not significant for spray plant protection products deposition. The number of nymphs per leaflet in the 2019/20 growing season was reduced with the used technologies, reducing from 10.9 to 3.0 nymphs per leaflet in the application with air-assisted and charged droplets, but not enough to differ from the untreated. On the other hand, the reduction was significant from the first assessment in the 2020/21 growing season. CONCLUSION: Air-assisted spraying plus electrically charged droplets, under the conditions of this experiment which corresponds to the application carried out in production areas, were not effective to affect whitefly control and soybean yield in comparison to the conventional application method. © 2022 Society of Chemical Industry.
Assuntos
Glycine max , Hemípteros , Animais , Ninfa , Folhas de PlantaRESUMO
BACKGROUND: The mite Brevipalpus yothersi (Acari: Tenuipalpidae) is of great importance in citriculture because it is a vector of the disease citrus leprosis. The frequency of application of a combination of pesticides has increased because of an increase in the occurrence of economically important pests of citrus. However, the combined effect of acaricide and other insecticides targeting B. yothersi is unknown. The objective of this study was to evaluate the effect of a combination of spirodiclofen and other insecticides on the control of B. yothersi. RESULTS: Analysis using spirodiclofen alone resulted in 97.22% efficiency in the control of B. yothersi on day 7 after application. A combination of spirodiclofen with either phosmet or imidacloprid resulted in 55% and 59% efficiency, respectively. A reduction in the efficiency of mite control by up to 42% was observed when the mites were exposed to a combination of acaricide with other insecticides. CONCLUSIONS: Application of a combination of spirodiclofen with phosmet or imidacloprid compromises the efficiency of acaricide in the control of B. yothersi. © 2018 Society of Chemical Industry.